1. Field of the Invention
The present invention relates to a coding method and a decoding method applied to the case where a voice signal is subjected to high efficiency coding or decoding, a coding device, a decoding device and a telephone device to which the coding method and the decoding method are applied, and various media on which processing data of the coding and decoding are recorded.
2. Description of the Related Art
There are known various coding methods in which a signal compression is conducted by utilizing the statistical characteristics of an audio signal (where the audio signal includes a voice signal and a sound signal) in the time domain and the frequency domain and the characteristics of the human auditory sense. The coding methods are broadly classified into coding in the time domain, coding in the frequency domain, analysis-synthesis coding and so on.
As examples of high efficiency coding of a voice signals, MBE (multiband excitation) coding, SBE (singleband excitation) or sinusoidal synthesis coding, Harmonic coding, SBC (sub-band coding), LPC (linear predictive coding), DCT (discrete cosine transform), MDCT (modified DCT), FFT (fast Fourier transform) and so on are known.
In the case where a voiced signal is coded by using the above described various coding methods or in the case where the coded voiced signal is decoded, it is sometimes desired to change the pitch of a voice without changing the phonemes of the voice.
In the conventional high efficiency coding device and high efficiency decoding device of a voiced signal, the pitch change is not considered and it is necessary to connect a separate pitch control device and conduct the pitch conversion, resulting in a disadvantage of a complicated configuration.